Excitotoxins in foods.

Evidence is reviewed pertaining to excitatory neurotoxins (excitotoxins) encountered in human food supply. The most frequently encountered food excitotoxin is glutamate (Glu) which is commercially added to many foods despite evidence that it can freely penetrate certain brain regions and rapidly destroy neurons by hyperactivating the NMDA subtype of Glu receptor. Hypersensitivity of NMDA receptors during development makes the immature nervous system especially sensitive to Glu excitotoxicity. On the other hand, elderly consumers are particularly sensitive to domoic acid, a powerful excitotoxic Glu analog that activates both NMDA and non-NMDA receptors. A high content of domoic acid in shell fish caused a recent food poisoning incident that killed some elderly victims and caused brain damage and memory impairment in others. Neurolathyrism is a crippling neurodegenerative condition associated with ingestion of a legume that naturally contains BOAA, an excitotoxic Glu analog that hyperactivates non-NMDA receptors. Thus, the human food supply is a source of excitotoxins that can damage the brain by one type of mechanism to which immature consumers are hypervulnerable, or by other mechanisms to which adult and elderly consumers are peculiarly sensitive.